mozilla-services/heka — pull request #1237 by hynd (2014-12-19 13:43:51+00:00)
Title: Allow Logger and Hostname to be overridden.

I'm not sure of the original reason why they couldn't be overridden, but it would be useful to have the ability to set Logger and Hostname from inside a Filter.
If they're not set, it'll default to the original 'SandboxFilter' Logger and Hostname from a fresh Message Pack.